Crossing Over
by GennaWeasley
Summary: It's just a semi-normal week at camp for Addi and Nico. But an egyptian amulet is causing problems for Addi and camp being camp, some oddness pops up I swear on the Styx that it's better than this summary may lead you to believe...


_A/N- Good gods, this was supposed to be short! it falls several weeks or possibly just days before my story Little Ones (that other PJO story I posted recently). The story focuses mainly on Nico and Addi, but there's some Kane Chronicles stuff thrown in. OH, and there's **finally** a decent explanation of Addi's popping in and out of different places habit. And an explanation for why Nico's been acting so odd... or rather, was acting odd in Little Ones.  
>As confusing as that author's note probably was, I hope you enjoy the story.<em>

Adria and her sister Melodite almost don't exist. No normal mortals would recognize their names, and very few demigods would. They are minor daughters of Poseidon, but though they've never been well known in mortal world, they're quite popular with the other gods and goddesses. Because they were so unknown, they were both able to spend time at Camp Half-Blood (and the Roman Camp) undercover as demigods.

* * *

><p>"Nico? Nico are you here?" Addi asked as she tapped on the door to the Hades cabin.<p>

Nico appeared almost out of nowhere. "Hello, Adria."

Addi shuddered. "Nico, just because you _know_ I'm not mortal doesn't mean that you can use my real name. What if someone heard you?"

"They'd be confused," replied Nico. "But I'll stop if you want me to."

"I would really prefer that," said Addi.

"So what brings you to the Hades cabin, Addi?" asked Nico.

"Mel's not here from Olympus yet," Addi answered. "Who else would I go to talk to?"

"So you're bored," observed Nico.

"Precisely," agreed Addi. "When did you get to camp?"

"This morning," Nico replied. "What about you? I stopped by a few days ago and you weren't here."

"I arrived very early yesterday morning," Addi answered. "And the cabin was a mess – Percy must've been to camp between the end of summer and now." Nico laughed. Addi continued, "Well it's good to know you're here – I should get back to cleaning up the cabin."

"See you later, Addi," said Nico. Addi waved and walked out of the cabin.

Addi wandered back to the Poseidon cabin and began picking up the random objects that were all over the floor. Most of it was trash, but there were also a few weapons and some armor. After she finished tidying up, she climbed up onto her bunk and picked up a book to read.

Percy Jackson loudly walked through the door. Addi looked up from her book and yelped.

"Percy!"

"Uh, hi?" He said. She vanished, book in hand.

A moment later, she reappeared on a bed in the Hades cabin. She jumped up off the bed and mumbled, "Oh, I forgot my book!" She vanished again and reappeared in her own cabin. "Hello little brother," she said to Percy as she grabbed her book. Then she disappeared and reappeared in the Hades cabin.

Nico grabbed her arm before she could vanish again. "Addi, why do you keep appearing and disappearing?"

"Percy!" she answered quickly.

"What about Percy?"

"He's back at camp earlier than I expected. We've met him all of twice and I really don't know what to say to him, you know?"

Nico stared at her for a moment. "Percy Jackson is the most approachable person I've ever met. Even _I_ never have a problem coming up with something to say to him – and as you're aware, my social skills are kind of lacking. Plus on top of that for the first year or so that I knew him I was a total brat to him, so he has plenty of reason to dislike me, but he doesn't. He's really a great guy – nothing to worry about."

Addi ignored him, pretending to be very interested with the bottom edge of her black tank top. It was her favourite – on the front the words "Camp Half-Blood" were printed in Ancient Greek (the lettering was orange) and on the back the same words were printed in Latin (and purple lettering). At that moment, however, the purple words on the back were covered with a dark green sweater because it was kind of cool out. She mumbled, "People keep telling me that."

"That's because he is," declared Nico.

"Well I'm still going back to Olympus for a day or two," said Addi.

"Good-bye, Addi," replied Nico. Addi nodded to him and vanished.

Addi next popped up on Olympus, right next to her twin sister.

"Hiding from Perseus, are we?" commented Mel.

"What? I, uh, no!" replied Addi. "Why would I be hiding from our 17–year-old baby brother?"

"You don't have good people skills," Mel pointed out. "Plus you two kind of just dropped into each other's lives and had to deal with the fact that you suddenly both have a brand new sibling to deal with."

"What's your point? So do you!" Addi replied defensively.

"Perseus and I haven't met yet. But you and I have both been watching him since he was 12, and I'm fairly certain that if he was introduced to another demigod elder sister we would be able to go on with our camp lives as we normally would," said Mel reasonably. "On top of that, my people skills are far better than yours."

"You spend far less time at camp than I do," argued Addi.

"That's irrelevant," replied Mel. "Now go back to camp and face your fears little sister!"

"Mellie, I'm not your _little_ sister. We're the same age!" Addi said.

Mel rolled her eyes. "Adria, dear, I was born first. Now go!"

"Fine," mumbled Addi. "But first I want to talk to Annabeth." Then she vanished again.

* * *

><p>"ANNABETH!" Addi exclaimed when she appeared.<p>

"What?" said a boy's voice. Addi looked around. She was in a room that she didn't recognize and there was a boy standing there – he looked about 14 or 15 years old.

"Uh-oh. You're not Annabeth… and this isn't camp… uh, where am I?" Addi asked uncomfortably.

The boy replied, "This is the Brooklyn house, or a little less specifically you're in the 21st Nome."

Addi gasped a little bit – for some reason hearing this place referred to as the 21st Nome felt like a sign that she shouldn't be there. She wasn't sure why, but something was tugging at her, telling her to leave. "I, uh, usually my aim is better than that. Brooklyn, you say? Yeah, my aim is usually far better than that."

"Okay?" the boy said. Addi looked around the room nervously before disappearing again.

* * *

><p>"Oh my gods," Addi muttered under her breath when she reappeared. "I'm done with <em>that <em>for the day. Oh, that was so weird…" Then she spotted Annabeth. "ANNABETH!"

The blonde demigod turned around. "Addi! Hi!"

Addi ran to catch up with Annabeth, who was walking to the arena with the Athena cabin. To one of Annabeth's cabin mates she called, "Thomas, can I borrow Annabeth for a moment?"

"I don't see why not," Thomas replied. "We'll be training for the next hour or so. See you in a little while, Annabeth."

Addi smiled and pulled Annabeth away. "Beth, you're supposed to warn me when Percy's going to be at camp!"

"Oh my gods! Addi I'm so sorry! I completely forgot that I promised to tell you he'd be here," Annabeth replied apologetically. "Oh… he's here, isn't he?" Addi nodded.

"Nico says I should talk to Percy," Addi said. "More precisely I was told to 'face my fears' – but I'm not scared of him!" Technically, Nico had never said that she was afraid of Percy – but Annabeth didn't know that Addi was a goddess. That meant that she didn't know that Addi had just popped back to Olympus and been sent right back by her sister. Addi sighed and continued, "Alright. Go back to the Athena cabin kids – I'll go talk to my brother now."

Annabeth ran off to catch up with her cabin mates and Addi turned to walk back to her cabin. She took a deep breath and moved toward the door to the Poseidon cabin. Halfway there, she changed direction and walked to the Hades cabin. When she stepped through the door, Nico looked up from the book he was reading.

"I thought you were going back to Olympus?" Nico said confusedly.

"I did," replied Addi. "Mel made me come back. She said something about facing my fears – which is completely ridiculous by the way, I have no reason to by afraid of talking to my 17-year-old half-blood baby brother – and sent me right back over here."

Nico chuckled. "Percy's really a great guy, Addi."

"I'm sure. But I'm less than enthusiastic about spending time with the brother I just met last October," Addi replied.

"I thought you said you and Mel had been keeping an eye on him," said Nico confusedly.

"We were, but that's not the same," said Addi. "Moving on. Nico, can I stay here for a few days? Until I'm a little more comfortable with my little brother?"

"Addi, that's **so** against the rules," answered Nico.

"Uncle Hades loves me – you know, in his own way – and Chiron knows I'm a goddess. He shouldn't mind if I bend the rules," Addi said. "There might be a few raised eyebrows from other campers, but who cares?"

Nico considered this for a moment. "Alright," he said. After all, she was one of his two favourite cousins. Of course, his other favourite cousin was the person she was hiding from – but Nico chose not to say that.

"Thanks, Nico! I'll be back in a few minutes," Addi said. She ran out of Nico's cabin and straight to her own.

Percy was unpacking his things in the Poseidon cabin. When she saw him, Addi froze in the doorway.

"Hi," he said. "Your name's Addi, right?"

"Yeah," she replied. She added, "You're Percy?" even though she already knew.

"Yep," answered Percy. "This is kind of weird for me – I've never had a sister before."

"Oh thank the gods, it's not just me!" Addi said. "I've kind of been avoiding talking to you, because I wasn't sure what to say – I still don't. Nico and Beth say you're nothing to be scared of, but I keep telling them that I'm not scared of you, I'm just not sure how you've reacted to suddenly having an older sister."

"I'm a little confused, but I've seen weirder stuff happen," Percy replied. Addi started to gather some of the things she'd need when she was staying in the Hades cabin – clothes, a toothbrush and the like – and put them in a beat up black backpack.

"Going somewhere?" said Percy.

Addi nodded. "Sort of." She continued to gather her stuff. Realizing something, Addi paused and looked up at Percy. "Nico tells me that you two sometimes do activities together, since neither of you have any cabin mates most of the time."

"Yeah, we do," said Percy, not quite sure where the thought had come from.

"Maybe I'll see you later then," Addi replied cryptically. Then she flung the backpack over her shoulder and walked out of the cabin.

Percy still didn't quite understand Addi. A few months ago, he'd been at Camp Half-Blood for a long weekend in October with Annabeth and when he'd walked into his cabin she'd been there. Annabeth recognized her and gave her a hug, and Addi had looked so comfortable in the cabin, like she'd been living there for a long time. Annabeth had introduced them, and Addi had awkwardly said, "Hello, little brother!" before running off. Annabeth had confirmed that she was, in fact, older than he was – which seriously confused him. Why hadn't she been involved with the fight against the Titans? Not that it really mattered anymore – that was all over. But Percy was planning on spending his spring break figuring out who his sister was.

Percy's thoughts were interrupted by Annabeth, who was standing at the door. "Seaweed Brain, did you do something stupid? I just saw Addi run off with a backpack. She's not leaving camp, is she? What did you do?"

"Relax, Annabeth, I didn't do anything!" Percy exclaimed. "I have no idea where she's going, but she said she might see me later, so I doubt that she's leaving camp."

"Oh," replied Annabeth. "Good."

* * *

><p>Addi had run straight to the Hades cabin. She dropped her backpack next to the only bed in the cabin that wasn't occupied by Nico. He looked up from his book when he heard the dull thud of the bag hitting the floor.<p>

"Hey Addi," he said. "It's almost dinnertime." Before Addi had time to respond, they heard a horn in the distance, calling them to go to dinner.

"Nice timing, Nico," said Addi. Together, they walked to the dining pavilion. Nico started toward the Hades table, but Addi froze.

"Is something wrong, Addi?" asked Nico.

"Where should I sit?" Addi mumbled.

Without even pausing to think, Nico replied, "At the Hades table, with me. We always eat together when we're both here – Chiron's given up on trying to send you back to your own table. Plus right now you're like an honorary member of the Hades cabin anyway."

"It's just… I don't want Percy to have to eat alone, you know?" Addi responded.

"Do you _want_ to sit with him?" asked Nico.

Addi shook her head. "Not alone," she answered. "Nico, why don't you sit with us at the Poseidon table?"

Nico replied, "Addi, that's not all-"

"No less allowed than me sitting at the Hades table, Nico," interrupted Addi. "This way Percy won't be sitting alone, you won't be sitting alone and I won't be sitting alone with Percy. It's brilliant."

Nico chuckled and followed her over to the Poseidon table. Percy was already sitting there when they sat down. Percy looked confused to see Nico with Addi.

"Uh, you guys know that's not allowed, right?" Percy pointed out.

Addi and Nico looked at each other and then back to Percy in fake confusion. Addi said, "What's not allowed?"

Percy came surprisingly close to believing that they didn't know, Nico could see it on his face. Then Nico and Addi burst out laughing. Percy interrupted their hysterical laughter. "Seriously, Nico sitting here could get us into trouble."

Nico and Addi looked at each other again. Nico quietly said, "Well, he hasn't been here."

"If he had been we would've had this discussion long ago," replied Addi, just as quietly.

Nico chuckled. "We did, remember?"

"Right, Beth lectured us for about half an hour," agreed Addi.

"What are you two talking about?" interrupted Percy.

"We do this all the time," Addi and Nico said simultaneously.

"What?" asked Percy.

Annabeth, who was walking past with a plate of food in her hand, said, "Don't question it. Everybody else has given up wondering how they get away with it every day."

Nico glanced at the table and saw that there was food in front of them. He, Percy and Addi all stood up and followed Annabeth to the fire.

"The strawberries," Addi whispered to Nico. He gave her a look of confusion. "The strawberries smell the best when they're burned."

Nico understood what she was telling him to do and pushed two of his best strawberries into the fire. Addi took a deep breath before pushing a few grapes off of her plate. That did not escape Nico's notice. "Addi, you just told me to do something then did something different."

"Ah," replied Addi. "The strawberries also _taste_ the best."

Nico chuckled as they walked back to the Poseidon table.

Percy was a few steps behind them. The first thing he'd noticed when he'd seen Nico for the first time since he reached camp was that the boy looked happier than Percy had ever seen him. He was laughing and smiling with Percy's sister. He was still dressed mostly in black and other dark colours – then again, so was Addi. Maybe that was part of why they got along so well, they had similar tastes. Percy remained distracted by watching them until Chiron stood up at the end of dinner to tell everyone to go get ready for Capture the Flag.

Percy walked back to the Poseidon cabin to get his armor and sword. He expected to be followed by Addi, but she and Nico both went off in another direction. When he saw them again, they were dressed in armor and holding weapons. The Poseidon and Hades cabins were both allied with the Athena cabin. Annabeth had declared that Addi and Nico would be the main part of the team trying to get the flag, and that several other pairs would distract the Ares team. Percy and Annabeth were one of those teams.

As soon as the game began, Nico and Addi vanished into the shadows. When they found the enemy flag (which took them a while), neither of them even drew their weapons. Almost silently, Nico stepped into the light just long enough to grab the flag and then faded back into the shadows. Addi held onto the flag as they carefully moved toward the border between the two sides. When they crossed the creek, the flag in Addi's hand turned black to represent the Hades cabin.

"Nico, if that's not proof that I'm allowed to be in the Hades cabin right now, nothing is!" Addi exclaimed when she saw the banner.

"Great," said Nico.

Just then, Percy & Annabeth ran over to the two members of the Hades cabin. Percy shouted, "What on earth just happened?"

Addi loudly replied, "We won!"

"Not that," said Annabeth. "Addi, you're in the Poseidon cabin, but instead of the flag turning blue with a trident on it for the Poseidon cabin, it turned black like it would have if Nico was holding it."

"Oh," Nico said. "I, uh, I really don't know why that happened."

"Maybe 'cause Death Boy here was the one who did the actual flag capturing?" suggested Addi.

"That's not how it works," replied Annabeth. "There's usually no difference between who carries it over the border and who actually takes the flag to begin with, but if it's a different person it'll change to reflect the cabin in which the person who _actually_ carries it over the border."

"Short version: Addi's not in the Hades cabin. We're confused," Percy summarized. Before Addi and Nico could respond, other campers started to gather around the four of them, having realized that the game had been won.

Nico whispered, "Addi… the Hades cabin just won capture the flag."

"Yes it did!" Addi whispered back. "Let's go back to the cabin, though, I don't really like this crowd." Nico nodded in agreement and they snuck away.

Later, Annabeth and Percy went looking for Addi. Annabeth stuck her head into the Hades cabin to ask Nico if he knew where she was.

"Nico, have you seen Addi?" asked Annabeth.

"Beth, shh," said Nico. He pointed to what Annabeth had at first thought was a shadow, but now realized was Percy's black haired sister curled up under a black blanket on the bed across from Nico's.

Annabeth lowered her voice and said, "Why is she in here?"

"Ask tomorrow," whispered Nico.

Annabeth left the Hades cabin to find Percy. She saw him standing outside the Poseidon cabin and ran over to him. "I found her," she said.

Percy looked around. "Where is she?"

"She's asleep already," Annabeth replied.

"...Where?" asked Percy, after checking inside the Poseidon cabin.

"The Hades cabin," answered Annabeth.

"That's against the-" began Percy.

"Everyone else has gotten tired of telling them that," interrupted Annabeth. "Nico said he'd explain in the morning."

"If he's dating my sister, so help me I'll –" Percy started to say. Annabeth laughed. Percy said, "What?"

"First of all, Addi and Nico aren't dating – he's 13 and she sees him as a little brother as much as she deep down sees you as her little brother," Annabeth explained.

Percy interrupted, "That's because I actually _am_ her little brother!"

"Secondly, I'm quite amused that even though you've spent so little time around her, you still got all overprotective at the idea that she might be dating someone," Annabeth continued as though Percy hadn't spoken.

"Because she's still my sister, even if we haven't known each other very long," Percy said defensively.

"Yeah, she is," agreed Annabeth. "Good-night, Seaweed Brain."

Percy kissed her on the cheek, said "Good-night, Wise girl," and Annabeth walked away. Percy went into his cabin, changed his clothes and climbed into bed. As soon as he put his head down on his pillow, he fell asleep.

* * *

><p>The next morning, Nico woke up to Addi singing Happy Birthday to him. He mumbled, "Oh, come on, Addi. Can't I sleep for 5 more minutes? 's my birthday…"<p>

"I know it's your birthday, Nico," replied Addi, much too loudly in Nico's opinion. "I let you sleep in already, little one. Now let's go, breakfast started 5 minutes ago."

Nico groaned and rolled out of bed onto the floor. He looked up at his cousin, who was already dressed and ready to go. "I'm not changing my clothes until after breakfast."

"It's your birthday," said Addi. "I don't see why you shouldn't get to eat breakfast in your PJs, even if we're at camp. Plus your normal clothes don't really look too different from what you're wearing right now."

Nico stood up and walked to the dining pavilion with Addi. They sat down at the Hades table and ate breakfast. Addi, who later told Nico that she'd been up since about 5, was unusually energetic. Nico, on the other hand, almost fell asleep twice during breakfast. Addi had to catch him to keep him from accidentally using his waffles as a pillow. After breakfast, Percy and Annabeth found them.

"Why are you suddenly a member of the Hades cabin, Addi?" asked Percy.

Ignoring his question, Addi said, "Aren't you two going to wish Nico happy birthday?"

"It's your birthday?" Annabeth asked Nico.

"Yup," replied Nico. "I'm fourteen now."

"Happy birthday!" exclaimed Annabeth and Percy simultaneously.

Nico and Addi started to walk away, but Percy grabbed Addi's arm. "Addi," he said, "you didn't answer me."

"Alright, I guess I'll have to explain this eventually," said Addi. "I'm staying in the Hades cabin because I'm more comfortable around Nico than the little brother that I just met, okay? It's awkward and every time you see me, I can see the confusion that I know you feel. You wonder if I'm really older than you where have I been and why wasn't I a part of the Titan War?"

"I thought I hid that pretty well," muttered Percy.

"You did," agreed Addi.

Nico added, "It's hard to hide things from Addi, though."

"Anyways, I figured since I never get in trouble for switching tables and I do all of my camp activities with Nico anyway, it'd probably a good idea to switch cabins for a while," said Addi. "Now if you'll excuse me, I have somewhere I need to be."

Without waiting for a response, Addi walked away. When she knew she was far enough away that the others couldn't see her, she vanished.

* * *

><p>She reappeared in the same room that she had accidentally appeared in before. She looked around and realized where she was. She gasped, but before she could disappear again, someone grabbed her hand. She turned to see who it was, and saw that it was the same boy that she had met before.<p>

"Who are you?" they said simultaneously.

"You first," said the boy. "It's my room."

"I'm Addi," answered Addi, "and I'm really sorry that I keep popping up here – I don't know what's wrong. I usually don't have any problems getting from place to place."

"I'm Carter," the boy replied, "Carter Kane."

Addi, who had been struggling to get her arm free, froze. "…Kane?"

"You're not from the House of Life, are you?" Carter asked nervously.

"The House of – oh, no, of course I'm not," replied Addi.

"Then why are you here?" asked Carter.

Addi shook her head sadly, "I wish I knew. Something keeps pulling me here when I try to travel between where I was and where I was going."

"That's weird," said Carter. "The spells on this place should keep you out, not pull you in. I'll have to talk to Bast or Uncle Amos about that."

Addi pulled her hand away from Carter. "I've got to go; I have to get my friend's birthday present from my sister." Carter stepped back. Addi added, "I really hope that this doesn't happen again, I feel like I'm invading your space – which is made all the worse by the fact that we really only just met."

Just before she was about to disappear, Addi stopped and looked at Carter again. "I recognized your name when you said it, but I only just remembered where I've heard it before. You once hosted the Egyptian god Horus, right?"

"Uh, yeah, how did you know?" Carter replied.

"Gods talk," Addi answered. Then she disappeared.

* * *

><p>"…And she just said 'gods talk' and then vanished!" Carter finished. He was retelling the events of Addi's visit to Sadie, Bast and the trainees. Zia was elsewhere.<p>

"That's odd," observed Jaz.

"I've never seen a magician who could just appear and disappear without a portal or anything," said Walt.

Sadie asked, "What did she look like, Carter?"

Carter closed his eyes, trying to picture her. "She had black hair, dark brown eyes and pale skin and she was wearing this black t- shirt that had orange writing on it that I didn't understand."

"That's what you get for not going to school for six years," said Sadie. "You couldn't even read a t-shirt!"

"No," replied Carter, "It was in another language that I wasn't familiar with."

"Oh."

* * *

><p>"I'm confused," said Nico. He understood Addi's first present to him – a black t-shirt with "Camp Half-Blood" written on the front in Ancient Greek and "HADES CABIN" on the back in English (both in orange), just like the one Addi was wearing – but he was now holding a pin that looked like a tiny metal masquerade mask and he really didn't get it.<p>

Addi looked around to make sure the cabin was empty before quietly saying, "My symbol of power is a masquerade mask. If you have that pinned somewhere on your clothes when you're in trouble, I'll know and I can try to help. Okay, little Nico?"

"Not so little anymore," replied Nico. "Thanks, Addi." He noticed that she had a clip in her hair that was very similar to the pin he was holding.

"You're welcome, little cousin!" Addi responded. She hugged Nico tightly.

"Adria, you're crushing my lungs!" Nico joked. Addi released him.

She frowned at him for a moment. "Nico, honey, you promised you wouldn't call me that."

"It makes you listen," he replied.

She punched him lightly on the shoulder. "Well cut it out, little cousin!"

"Hey, Addi, can I tell you something?" asked Nico, after they had sat in silence for a moment. Addi nodded. Hesitantly, he continued, "Actually I want to ask for some help."

"Go ahead, Nico," Addi prompted.

"See, I… I have a crush on this person… and they're dating someone… and even if they weren't they'd never be interested in me," said Nico. "And it really sucks and I need someone to talk to."

"Talk to me, then," replied Addi. She was kind of surprised that Nico was telling her anything about his crush – even though they were best friends, Nico still didn't talk about stuff like that much. "Are you going to tell me who it is or are you going to continue to be super vague forever?" Nico looked around to make sure that they were alone and then whispered a name into Addi's ear. Addi put her arms around her cousin and said, "Oh, Nico honey, that must be awful…"

"Yeah," replied Nico. "They're always around. Always."

"Okay we need a codename so you don't have to be so vague all the time," Addi said. "How about… Priscilla?"

Nico chuckled. "Sounds great, Addi."

They sat there for a while silently. Eventually, Nico fell asleep even though it was the middle of the afternoon. Addi still had her arms around him. After a little while, Percy stuck his head into the cabin.

"Hey Addi? There's a guy in our cabin who's looking for you," he said.

"I'll be there in a minute," replied Addi. She stood up and carried Nico over to his bed. Then she picked up a piece of paper and a pen to write Nico a note, and then remembered that his dyslexia did not agree with her handwriting – which was pretty much illegible to everyone, not just the half-bloods at camp. She dropped the pen and paper on the dresser next to the bed and whispered to Nico, "I'll be back later, little brother." She paused. "I mean little cousin." She kissed him on the cheek and walked to the Poseidon cabin.

Sitting on the unoccupied bottom bunk under Addi's bed was a blonde boy, who looked about 17 or 18. "Hello Adria," he said.

Addi sat next to him. "Don't let any of your kids see you, Apollo."

"No greeting, Addi?" replied Apollo.

"No," answered Addi. "Why did you tell my brother to come pull me away from my cabin?"

"Isn't your brother your only cabin mate?" asked Apollo.

Addi replied, "I was in the Hades cabin with my favourite cousin. Now what do you want?"

"I thought _I_ was your favourite cousin," said Apollo. He sounded a little bit hurt. "But I was hoping that you'd be interested in going to Aph's party with me this weekend."

"No," answered Addi.

"Just no?" said Apollo.

"Here, let me explain," snapped Addi. "One, I will be at camp during the party – and I already told Aphrodite that. Two, you're asking me to go as your date and I dumped you 8 years ago!"

"I was hoping that you'd gotten over that little fight and maybe we could start dating again," admitted Apollo quietly.

"Apollo, you cheated on me! MULTIPLE TIMES!" replied Addi angrily. "And if you want proof I could walk to the cabin two doors down and grab one of your children that was born **while we were dating**!"

"Uh… how about no?" said Apollo.

"Now if you don't mind – and even if you do mind I'm leaving anyway – I'd like to get back to the Hades cabin before Nico wakes up," Addi said angrily.

"What, are you dating the son of Hades now?" asked Apollo in a similarly annoyed tone of voice.

Addi laughed. "No. But you know what, Apollo? I care about Nico" she paused "and Percy more than I have ever cared about any boyfriend I've ever had."

"Even me?" asked Apollo.

"Especially you," answered Addi. She stood up and started to leave. Then she turned around and added, "Get out of this camp, Apollo. I come here to escape life on Olympus – it'd be best if the rest of you Olympians would leave me alone while I'm here."

Without waiting for a response, she stormed back over to the Hades cabin and flopped onto her bed. Nico rolled over on his bed to look at Addi across the room.

"You're mad," he observed sleepily. "What's wrong?"

"Nothing," lied Addi, and even though her specialty was concealing things she was sure that Nico could tell she wasn't telling the truth.

"Tell me," ordered Nico.

"Nico, sweetie, it's your birthday," replied Addi. "I'll tell you tomorrow."

Nico sat up and stretched. "Fine." He walked over to Addi's bed and sat down next to her. "Um, Addi, I could've sworn that I heard …Priscilla's voice earlier. Was she here or am I just imagining things?"

"Yeah, she popped in to tell me something," replied Addi. She stood up and led Nico toward the dining pavilion. "We missed lunch, little cousin. It's nearly dinner time." They heard a horn in the distance as they approached the dining pavilion. They sat down at the Hades table and ate their food.

Before they went back to the Hades cabin, Addi told Nico that she wanted to talk to Percy and that she'd catch up with him later.

"Okay," Nico replied. Addi ran over to the Poseidon table and sat down across from Percy.

"Hi Addi," Percy said confusedly.

"Hey Little One," she replied. "We need to talk about who you let into the cabin."

"That was Apollo," said Percy. "I couldn't exactly tell him to get out, could I?"

"I really would've appreciated it if you had," Addi said.

"I'm not exactly on the best terms with most of the gods," Percy pointed out. "I think they appreciate the fact that I saved all their butts in the Titan War, but I was kind of rude to them afterwards. I'd rather not make it worse."

"Look, Percy, if _any_ other god comes to our cabin looking for me, go ahead and let them in." Addi said sadly, "But not Apollo. Never Apollo."

"Why?" asked Percy hesitantly.

"It's not important," replied Addi quickly. "Just never let him near me again, okay Percy?

"Alright," responded Percy.

"Thanks," said Addi. "I'm counting on you to not let this happen again, Little One!" Then she jumped up and walked just far enough away from the dining pavilion that no one still eating could see her and she vanished, hoping to get back to her cabin more quickly.

* * *

><p>For the third time, she found herself in that room – Carter's bedroom. "What in Hades is going on here?" said Addi loudly.<p>

This time, the room was empty – that is, until Addi shouted. Then Carter, followed by two younger girls, came flying into the room. One of the girls said, "Who are you?" to Addi. She had a British accent and was holding what Addi recognized as an Egyptian magician's wand.

Addi looked at Carter. "What's going on, Carter?"

"No," he replied.

"Is this that girl you were telling us about?" asked the other girl.

"Yeah, Jaz, it is," answered Carter.

Addi looked around the room. "Something keeps pulling me here. I intend to figure out what it is before I return to camp." Then she spotted an amulet that was sitting on the dresser. She walked over and picked it up. "Where did this come from?"

The first girl who had spoken said, "Anubis gave it to us. He said it would help us find allies."

"Sadie, maybe you shouldn't tell the strange girl who just appeared in Carter's room that we've had contact with a god. What if she's from the House of Life?" Jaz, the second girl, suggested reasonably.

"I'm not from the House of Life," replied Addi.

"Then are you an ally?" asked Sadie.

Addi looked at the amulet in her hand. "I'd love to help you guys, really, I would. I know who you are now, too, since Carter told me what his name is. I'm sorry, but I can't help. Anubis knows that…"

"How do you know that _you_ were the person that Anubis wanted us to meet?" Carter asked.

"Because this," Addi held up the amulet, "is mine."

"What?" said Sadie loudly.

Addi took a deep breath. "A long time ago, probably before any of you were born, Anubis and I were friends. We were quite close, but my father and uncle were never the biggest fans of you Egyptians."

"Wait a minute," interrupted Carter. "Before we were born? But you only look a few years older than me!"

Addi rolled her eyes and ignored his comment. "Anubis gave me that amulet so that he'd always be able to help and protect me." She laughed. "As if _I_ need protecting. Anyways, my dad and my uncle – well mostly my uncle" there was thunder and lightning outside "Oh shut up!"

"What?" asked Jaz.

"My uncle doesn't like that I'm talking about him," explained Addi. "I don't know if it's because you're mortals or because I'm telling a story that makes him seem like the bad guy –" There was more thunder. "Ah, the second one."

"Go on with the story," Carter said.

"Well my dad and my uncle didn't like that I was wearing an Egyptian amulet," Addi continued. "My other uncle defended me and my friendship with Anubis – he's always had a soft spot for your death god – but my father told me that I couldn't continue to be friends with Anubis. He and I were in a graveyard talking, and … we got into a bit of a fight. I had to defend my father and Lord Zeus – they're my family!"

"Lord _Zeus_?" repeated Jaz. "Your uncle is _**Zeus**_?" They heard more thunder and there was a flash of lightning.

"Be careful about using his name, he's been kind of irritable lately." Addi continued, "At some point in the argument, I threw the amulet on the ground. Anubis must want me to convince the demigods to help you… but I can't. He knows I can't. Lord Zeus and my father don't get along with the Egyptian gods and I don't want Nico or Percy or Beth or any of the others to get caught up in that."

"Oh," said Carter, "We understand."

"I'm sorry," said Addi. She walked a few steps away, mumbled, "Lord Zeus will _not_ be happy with me for telling them…" and vanished.

* * *

><p>"I was really expecting you to use the door," commented Nico when Addi appeared on her bed.<p>

"Don't get your hopes up," said Addi. "I've figured out what was causing problems before. I can appear and disappear whenever and wherever I want to again." She held up the amulet for a moment, then put the chain around her neck.

"It was causing you problems, why are you putting it on?" asked Nico reasonably.

"It was causing problems because it was elsewhere," answered Addi. "Now that I have it with me it should be fine."

"What _is _it?" asked Nico.

"An old gift from an old friend," replied Addi. "I'll explain in the morning."

"Addi, it's not that late," Nico pointed out.

Addi yawned and responded, "Well I'm tired. I've been getting up awfully early lately."

"Alright, Addi," said Nico. Addi changed into her pajamas and curled up on her bed. She fell asleep almost immediately. Nico crossed the room and pulled the black blanket over her. "Good night, Addi."

Nico walked out of the cabin to look for Percy, who he found by the beach. "Hey Percy!"

Percy turned around and waved to Nico. "Hi Nico! Where's Addi? You two have seemed pretty inseparable recently."

Nico chuckled. "She's asleep."

Percy checked his watch. "It's only 8 o'clock!"

"I get the sense that she doesn't sleep well at home," replied Nico. "On top of that, she woke up at five this morning."

"Why?" asked Percy.

"Why doesn't she sleep or why did she wake up at five?" responded Nico.

Percy thought for a minute. "Both."

"I have no clue what possessed her to wake up at five," Nico answered. "But as for her not sleeping… as I understand it, she lives with and near some energetic people who may or may not be nocturnal."

"Ah," said Percy. "So what brings you to the beach?"

"I didn't feel like sitting around in the cabin with no company except for your sleeping sister," replied Nico. "I don't really have that many good friends, and I can usually find you here."

"Well do you want to swim?"

"Sure."

* * *

><p>The next morning, Nico woke up and was ready for breakfast before Addi had even started to wake up. When he heard the horn that informed the campers that it was breakfast time and Addi was still asleep, Nico started to get a little bit worried. Addi was usually up long before Nico, no matter how tired she had been the night before. He shook her shoulder in an attempt to wake her up. "Addi… Adria, wake up. It's time for breakfast, sis! I-I mean… Well I don't usually call you cousin or anything like that. But I guess you're more like a sister to me than a cousin anyway. That's not important right now. Wake up, I'm hungry." Addi rolled over. Nico gave up on waking her up and went to breakfast.<p>

For the rest of the day, between activities Nico would run back to the Hades cabin to see if Addi had woken up. Nico was pretty sure that he was confusing and/or concerning Percy by running off after everything without explaining. After they had spent an hour training in the arena and were about to walk over to the climbing wall, Percy grabbed Nico's arm before he could run to the Hades cabin. "Nico, where do you keep running off to?"

"Hades cabin," answered Nico. "When Addi wakes up I want to make sure that she knows where we are."

"Wait a minute," said Percy, "Addi's still asleep?"

"Yeah," replied Nico. "Didn't you wonder why she wasn't with us?"

"It didn't really cross my mind," answered Percy honestly. "She doesn't seem to like me much."

"She likes you, don't worry. The big sister thing just kind of freaks her out. But she's a better big sister than she thinks she is," Nico said.

Percy didn't say anything for a moment. He just thought about what Nico had said. Then he replied, "I'm sure she'll be able to find us at the climbing wall. I've hardly gotten to hang out with you without my big sister around since Christmas!"

Nico chuckled. "Alright. I'll check on her later."

"Great!" exclaimed Percy and he led the way to the climbing wall.

Two days later, Nico and Percy walked into the Hades cabin after lunch. They both glanced concernedly at Addi, who hadn't woken up since she returned from talking to the Kanes. Once she had slept through a whole day, Percy and Nico started to worry a little bit. Nico knew deep down that it was unlikely that there was anything seriously wrong with Addi, but he was still a bit concerned.

"It's a good book, Percy!" Nico said. "If Addi was awake, she'd agree with me. She even leant me her copy that's in Ancient Greek so that I could read it."

"First of all, Ancient Greek is pretty tough to read," replied Percy. "Second of all, where did she even get a copy of And Then There Were None in Ancient Greek?"

"I have no idea," Nico lied.

"I still don't want to read it," Percy said.

Nico picked up the book that was sitting on Addi's dresser. "Come on, Percy! It's a mystery and it's kind of creepy and it's a really good book. Why won't you read it?"

Percy shrugged. "I don't like books much. Plus I think my English class is supposed to read it soon."

Addi yawned and mumbled, "'s a good book, Little One."

"Addi?" said Nico. He sat down on the bed next to her. Addi stretched and sat up.

"Morning Nico," she said. "You know, Percy, you really should read that book. It's my favourite."

"You've been asleep for three days," observed Percy, "and the first thing that you did when you woke up was tell me that I should read a book?"

"Three days?" repeated Addi.

"Well, more like two and a half," corrected Nico.

"I kind of lost track of time," Addi said. "Sorry, little ones."

"Lost track of –" began Nico.

Addi interrupted, "I was otherwise occupied, cousin."

Nico glanced at Percy, who looked confused, before whispering, "What were you doing, Adria?"

"A few things," replied Addi quietly. "I helped my sister with something, talked to Aph about how she needs to stop torturing you and my brother and avoided my ex."

"Okay then," said Nico.

"I'm confused," declared Percy.

"Somehow that doesn't surprise me," Addi commented. "By the way, Nico, there's someone I want you to meet later."

"Who?" Nico asked.

Addi glanced at her brother before saying, "I'll tell you later, little cousin. So what are the Poseidon and Hades cabins up to next?"

"Canoeing!" replied Percy happily.

* * *

><p>That evening, Addi pulled Nico away from Percy after dinner. "Field trip time, cousin!"<p>

"Uh, okay?" Nico said as she dragged him toward the forest. As soon as they were far enough away from the dining pavilion that Nico was sure no one could see them, Addi grabbed his wrist and the camp disappeared. The next thing he knew, they were standing in a cemetery somewhere in New York.

"Addi, why are we here?" asked Nico.

"We're looking for someone," she answered.

"Adria," said a voice behind them. Nico and Addi turned around to see a teenage boy who looked like he could be Nico's older brother.

"Hello Anubis," Addi replied calmly. "Nico, meet Anubis. He's the Egyptian god of death. I thought you might be interested in meeting him, and since I was already planning to come talk to him, I brought you with me."

"Who is the demigod?" asked Anubis.

"My cousin," answered Addi, "Nico di Angelo, son of Hades."

"Nice to meet you," Nico and Anubis said simultaneously.

While Nico and Anubis had been speaking, Addi had taken off the amulet she had taken from the Kanes. "Anubis, why did the Kane children have this?"

"I was hoping that you could help them," replied Anubis.

"You knew that I couldn't," said Addi. "You remember what happened…"

"I know," Anubis responded.

Addi looked at him for a moment before saying, "I _know_ you know. So why did you give it to them?"

"Because I needed to talk to you," he answered. "I've regretted that argument since the moment you ran off, Adria."

"I regretted it too, Anubis," replied Addi. There was a faint rumble of thunder. She shouted, "Shut up, uncle! I don't care anymore! I'll be friends with who ever I want to be friends with!"

"I take that as you saying that you want to be friends with me," said Anubis.

"Of course," Addi said. "We have an awful lot of catching up to do." She absentmindedly played with a sun shaped charm on the charm bracelet she always wore.

"Still dating Apollo?" guessed Anubis when he noticed this.

"What?" said Addi. Then she realized what he was referring to. "Oh, no… I just haven't taken the charm off the bracelet. It's a reminder not to do anything that stupid ever again."

"Ah," said Anubis.

Nico kind of drifted off and stopped paying attention, but his attention snapped back to the two gods when Anubis handed Addi a charm for her bracelet that looked like a jackal and she giggled and kissed him on the cheek. At that point Nico was pretty sure he'd missed part of the conversation, but he was also pretty sure that he didn't really want to know what had been said. That thought was confirmed when he saw the girl he looked up to and thought of as a sister kiss a 5000-year-old Egyptian god. Admittedly, she was probably somewhere around Anubis's age, but Nico didn't really want to think about that.

"ADDI! I really don't want to see you making out with the Egyptians' god of death!" exclaimed Nico. The thunder that followed Nico's statement told him that their uncle agreed.

Addi looked up at the sky. "Oh, Lord Zeus might _actually_ kill me this time… Not that I have much of a problem with that – I spend so much with you death god types." Nico and Anubis both laughed.

"Addi, we should go, Percy's going to be looking for us soon," Nico said.

"Fine," said Addi. She kissed Anubis good-bye, grabbed her cousin's wrist and then vanished.

They reappeared outside the Poseidon cabin. Nico said, "Percy said he had something he wanted to tell us after dinner."

Percy ran up to them. "Guys… I … Annabeth… Can we talk for a minute?"

Addi nodded and walked into the Poseidon cabin. She sat down on the bunk underneath hers and was joined by Percy and Nico. "What's up, Little One?"

"Annabeth dumped me," he said.

"Are you okay?" asked Addi.

Percy nodded. "I think so… I mean… sort of."

Nico stood up and awkwardly patted Percy on the shoulder. "That sucks, Percy. I, uh, I'd love to stay and talk but I, uh, can't…" and he ran out of the cabin, colliding with Annabeth as he escaped the conversation. Percy and Addi heard him shout, "SORRY BETH!" without even stopping.

Addi hugged her brother. "I'm sure you'll be fine, little brother. You'll move on. I'm sure that there are people who have been waiting for the two of you to break up so that they can have a chance to date you."

"Great," said Percy sarcastically. "I'll just have to find one of them, then."

"They're closer than you think, little brother," said Addi.

* * *

><p>Percy did move on and find someone else – but that's another story.<p>

Addi and Anubis are still dating, much to the displeasure of Zeus and Poseidon (who still don't really get along with the Egyptian gods) and Apollo (who everyone says is still in love with Addi) – but they have the support of Hades and Osiris.

* * *

><p><em>AN - Okay, a few words of explanation. The title, "Crossing over" refers to Addi and Nico's (well mainly Addi's) habits of sitting/staying with/in cabins that are not their own. Addi is named after a particularly awesome bad guy (girl?) from Stargate SG-1, Adria (Vala's daughter, if you've seen the show). Melodite is the creation of one of my best friends, Julianna. Hopefully some of the stuff that may have raised questions with Little Ones have been explained now that you know what happens first. Addi's the goddess of concealment and hidden things (that's why people can't lie to her... they try, but she can see the truth anyway) and her sister is the goddess of bad weather. And good (but not good weather). There's no way to make those work in one sentence. They're obviously OCs, but I figure that if the Greek gods are still around, they've probably had godly children that aren't well known gods._

_Ridiculously long author's note number two is almost over, but I'm ending with yet another request for reviews. They help me improve my writing! =)_


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